At First Blush

“It’s fandemonium,” said Ms. Gorgeous, the YouTube beauty guru and comedian, leaning against a couch in the very, very important person section at BeautyCon, a summit for online beauty enthusiasts and the young women who love them, and exhaling as much as her crop top allowed.

“There were a couple girls that were crying when they came up to the meet and greet counter,” said Ms. Gorgeous (real name: Gigi Loren Lazzarato). Blonde and bubbly, she has courted nearly a million subscribers with frank, funny videos about subjects like her favorite foundation brush and the time she and her friends were pulled over for taking selfies by the side of the road. In the flesh, she inspired giddy jumps.

“It’s a 3-D image in real life,” said Ms. Gorgeous, 22. “You’re blinking and breathing in front of them.”

It was around 3 p.m. on a recent Saturday, and nearby, a battalion of burly security guards (from the same company contracted by the Emmy Awards, a publicist breathlessly noted) escorted Bethany Mota, another YouTube star, though a mob of frenetic fans. “Bethany, Bethany, I’m right here!” cried one girl, smartphone outstretched like a selfie-seeking tentacle as Ms. Mota, 18, squeezed by. When she turned and smiled, screams soared through the cavernous hall of LA Mart, little eruptions of enthusiasm that, if bottled, might feel like pressurized confetti.

More than seven million people subscribe to Ms. Mota’s YouTube channel, a compilation of hair, makeup and lifestyle advice videos. “You see the number online and you see people engaging on Twitter, but it’s so different seeing them in person like, ‘Wow, you’re real people that actually watch me,’ ” she said. “It’s the coolest feeling ever.”

There’s a critical mass of makeup mavens rising up online and spilling out into the real world, where they induce the type of hysteria formerly reserved for the Beatles and boy bands. Three years ago, BeautyCon, a new media start-up, seized on this and began an annual series of events where fans can meet their idols, participate in panel discussions, get tips on how to increase their own online presence and test the latest beauty must-haves. (Rhinestone unibrows, anyone?)

It’s day camp meets Sephora meets the “American Idol” live tour, all packaged in the pretext of empowering young women. Four thousand swarmed BeautyCon’s first New York summit in May; 6,000 showed up in August for the Los Angeles edition. Moj Mahdara, the chief officer of BeautyCon, calls it the start of a revolution — a “self-discovery movement,” she said, for “that girl who’s between 14 and 24, who’s positive and, like, not a hater and wants to be beautiful inside and outside.”

The mainstream fame machine is catching on. Ms. Mota was cast in the latest season of “Dancing With the Stars,” which premiered this week, and has collaborated on collections with the retailer Aéropostale. Kelly Osbourne, an E! host, invested in BeautyCon after speaking on a panel last year. (She and Ms. Mota teamed up for this year’s Los Angeles keynote address, which followed a panel called “Hi Haters, Bye Haters.”)

“I saw how supportive everyone was and how much great information and knowledge and positivity was in the room, and it took me aback,” Ms. Osbourne said. “I was just thinking, young women and people need more of this. They need more of this.”

BeautyCon was started by the YouTube personality Marina Curry in 2011. Last year, she approached Ms. Mahdara, who also runs the brand advisory firm Made with Elastic, to raise the profile of the conference, which at the time, Ms. Mahdara said, looked more like a trade show than a must-attend event for the masses.

“What we got involved with was a convention, what it is now is a media company,” Ms. Mahdara said.

She relies on the input of a key intern, Ella Carlson, 10. Ella spends about two hours a week in the company’s Hollywood offices, giving Ms. Mahdara and her team of 11 feedback on BeautyCon’s website and development. “I watch YouTube a lot,” she said.

Marketing is built into the concept: Months ago, YouTube stars (or YouTubers, as they’re called) started telling fans they would be attending BeautyCon, prompting a wave of young women to flag down the nearest parental figure and beg for a trip to Los Angeles.

Hayley Toro, 11, traveled to BeautyCon from Dallas with her mother; her cousin Luz Toro, 14, joined them from Arizona. “They’ve been talking about this almost since the beginning of the year,” said Hayley’s mother, Kim Toro. “It didn’t take a whole lot of convincing.”

Luz said she watches YouTube makeup tutorials “anytime I can, honestly, every second I can get.” What has she learned thus far? “It’s about not covering up your natural beauty, about showing it and enhancing it just a little,” she said.

Pressure can taint the positivity. In this arena, where anyone with a camera and an Internet connection can be an expert, many fans are trying to cultivate followings like their YouTube idols. Hayley Toro said she has dabbled in making her own makeup tutorials but “people are very judgmental. I’m still in the process of trying to make it good quality.”

For the Toro girls, as for the majority of attendees, YouTube tutorials have largely replaced glossy magazines as their go-to source for style information and inspiration. There’s the convenience factor (it’s a lot easier to master a fishtail braid with the aid of a smartphone and a mirror than with a bound, bullet-point list) and the fact that there’s greater diversity to be found online than in the pages of mainstream women’s magazines.

“They were always talking about white girls, like ‘This would look great with blue eyes,’ and I’m like, ‘I don’t have blue eyes,’ ” said Jasmine Wang, 22, whose dark brown eyes were rimmed with streaks of gold glitter. “It’s not going to work the same way.”

Wise to this, earlier this year, Elle magazine teamed up with BeautyCon, making Joe Zee, then its creative director, the moderator of a New York panel and setting up a pop-up salon at the Los Angeles meet-up, where young women scrolled through their smartphones as stylists ironed “Charmsies,” tiny glittery jewels with adhesive backing, into their hair. (Hearst, the parent company of Elle, also has a financial stake in BeautyCon.)

“This is the best-case scenario, that you get beauty enthusiasts and experts together in a place where they can just play,” said Emily Dougherty, Elle’s director of beauty and fitness, who sported her own set of Charmsies. “Everyone kind of leaves their irony at the door.”

The number of things a woman could do at BeautyCon boggled the mind and, at times, bordered on the bizarre. Carefree, a brand of panty liners, set up a station for screen-printing underwear. Even this cringe-inducing area of care inspired its own hashtag: #mymorningbeauty.

Nearby, the celebrity makeup artist Beau Nelson leaned over a girl in a pink tulle dress, demonstrating how to do a cat eye to a crowd of a few dozen. “I think that’s what a lot of girls have trouble with,” he said. “Whenever you’re trying to blend out a dark color, like how did it get all the way over here?”

Not far from him, the people at Project Beautiful, an online water cooler for YouTube beauty personalities, applied jewels to foreheads and brow bones. The bedazzled girls who bounced away recalled the Na’vi from the movie “Avatar.”

“It’s just to add, like, sparkle to your face,” said Jeaneen Mena, 20, who had a baby-blue rhinestone twinkling from the center of her forehead like a third eye. With a fresh henna tattoo on her left hand, she was contemplating getting a flash tattoo. “Flash tattoos are temporary sparkly tattoos,” she said. “That’s what I learned while I was getting my henna.”

Shana Hayes, 12, watched the scene casually, recounting her own experience making YouTube videos (“I didn’t have a lot of subscribers, like 300”) before stopping midsentence and swiveling her head around. “Oh, Mickieray22!” she squealed, referring to the 15-year-old beauty guru McKenzie Luskey (YouTube subscribers: north of 74,000). “I love her, she’s like, one of my favorite YouTubers.”

This, generally, was how conversations at BeautyCon ended — the sighting of a YouTube celebrity and the overwhelming urge to seize a selfie. “I took a lot of selfies,” said Aimee Song, whose popular blog Song of Style skews more Condé Nast boardroom than teenager’s bedroom. “ I took a lot of selfies. Inside the elevator, I took like 12 selfies, with every single person, which was cool, and then we decided do a group selfie, and then walking, it was like, two selfies per step.”

There were no nerves stopping these girls. For all the furor these YouTube characters cultivate, with their homespun advice and girl-next-door air, they are relatable to a degree that traditional celebrities are not. “She talks about them the same way she talks about the girls at school,” said David Voss, who brought his daughter Aubrey Voss, 11, to BeautyCon. “They’re not just celebrities to her, they’re reachable and touchable, and that’s what it’s been for her, I think.”

He paused and shrugged: “I mean, I don’t know, I’m the dad.”

Indeed, in this realm of fame, keeping it real is crucial. It becomes an artful dance for a personality like Ms. Mota, who would get mobbed if she were to wander the pink balloon strewn floor of BeautyCon alone. Instead, before her keynote address with Ms. Osbourne, she lounged in the V.I.P. area with her laptop, mother, father, sister and niece, shooting official BeautyCon portraits and grinning at the few fans who managed to sneak around the back to get a peek at her.

She employs other tactics, like posting Instagram photos of her family. “I think it’s important to show them parts about my life so that it’s not just, ‘I’m going to teach you about makeup,’ it’s also about who I am and what my interests are,” she said.

“It’s just about connecting with them in any way that I can,” she added. “Those are the things that attract people to each other and make them become friends. It’s similar interests.”